The present invention relates to a lighting device.
Japanese Utility Model No. 3159820 describes an example of a lighting device including a main power supply and a backup power supply. When the supply of power from the main power supply to a light source is interrupted, the light source is supplied with power from the backup power supply.
The lighting device of Japanese Utility Model No. 3159820 further includes a main light source and a backup light source. The backup light source is formed by an LED. When an abnormality occurs, the low power consumption backup (LED) light source is used so that the backup power supply, which is a rechargeable battery (battery cell), may be used for a relatively long time.
There is a demand for a lighting device that improves visibility under a mesopic vision environment. Japanese Laid-Open Patent Publication No. 2005-11812 discloses a lighting device that uses three LED light sources having different wavelengths and executes spectral control to generate light in accordance with a mesopic vision environment. Further, the lighting device of Japanese Laid-Open Patent Publication No. 2005-11812 uses LED light sources, and thus, consumes less power than fluorescent lamps and incandescent light bulbs.
Such a lighting device uses three types of LED light sources having different wavelengths to improve visibility under a mesopic vision environment. The LED light sources increase the number of components.